Steer-by-wire systems are known from the prior art which can also be used in ship control engineering. In systems of this type, the steering commands input via a steering unit are detected by a sensor and passed, via a control unit, to an actuator, which executes the steering command. In an advantageous manner, no mechanical connection exists between the helm (steering wheel) and the rudder and/or in the case of a motor vehicle, between the steering wheel and the steered wheels.
In ship control engineering, the steering units connected to the helm are usually hydraulically actuated, which has the adverse result of poor dynamics as well as high maintenance costs.
A steer-by-wire ship control system is known, for example, from U.S. Pat. No. 6,431,928 B1. In the known system, an electric motor is used to rotate the entire propeller propulsion unit via a mechanical power train, wherein the electric motor is controlled by a control unit, which is connected firstly to the steering unit to receive steering command information, and secondly to a sensor which detects the steering position information.
From U.S. Pat. No. 7,137,347 B2 a steering unit is known for a steer-by-wire ship control system which has a mechanically flexible steering device, for example a helm, a sensor to detect the rotational motion of the helm, and a stop mechanism for blocking of any additional rotational movement of the helm to starboard or port when the ship rudder has reached an extreme starboard or port position.
From EP 1770008 A2 a steer-by-wire ship control system is known which comprises at least two steering units. In this case, the rudder is actuated by means of a hydraulically operated actuator based on the steering signals, which are generated by the steering unit that requires the faster movement of the rudder. In the known system, the steering units each comprise a helm, which is connected to a control device, which in turn is connected to a control network.
Furthermore, in the case of actuation or rotation of the helm as a function of signals from a sensor to detect the rudder position, it is provided that the steering devices produce a mechanical resistance by means of a coupling, wherein the resistance is greater the closer the rudder approaches an end position. Once an end position is reached, the mechanical resistance on the helm is adjusted such that an additional rotational movement thereof in the same direction is not possible. This is affected by means of a coupling, which in the fully closed position allows no rotational movement of the helm.
Furthermore, from U.S. Pat. No. 6,843,195 B2 a control system is known for an outboard motor in which the quotient “implemented steering angle/steering angle input via the helm” decreases with increasing speed.